A data stack is indeed not required -- see Om (experimental): http://concatenative.org/wiki/view/Om http://concatenative.org/wiki/view/Om It uses prefix notat

A data stack is indeed not required -- see Om (experimental): http://concatenative.org/wiki/view/Om http://concatenative.org/wiki/view/Om It uses prefix notation: instead of a data stack, each function takes the remainder of the program for rewriting.